The present invention relates to a silver halide (hereinafter referred to as xe2x80x9cAgXxe2x80x9d) photographic material which is useful in the field of photography, and particularly relates to a photographic material improved in sensitivity and image quality.
It has been required to further improve sensitivity and image quality of photographic materials. When tabular AgX grains are used in photographic materials, the main planes of tabular grains are oriented in parallel to the support, leading to the thinning of the AgX emulsion layer. The improvement of sharpness and speed-up of development have been contrived by making use of this property. There is a maleficent effect of image quality deterioration due to light reflection by interrelation between a tabular grain and an incident light. However, further improvement of sensitivity and image quality has been required by dissolving this problem.
Coherence of the thickness of a tabular grain and a monochromatic light is described in Research Disclosure, No. 25330, May (1985), but there is no description with respect to the specific way of improvement by making use of that characteristic.
There are disclosed in JP-A-6-43605 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d) the fact that the thickness of the tabular grain in the photosensitive layer farthermost from the exposure light source makes the light reflection in the photosensitive spectrum region of the emulsion the smallest, and the embodiment of also making the thicknesses of the tabular grain in other photosensitive layers optimal in the photosensitive wavelength region of the photosensitive layer to make the light reflection the smallest, but the improving effect of sensitivity and image quality is small only with these embodiments.
When reflection occurs by the incident light from a dispersion medium layer to an AgX layer, in general, the electric field vector of the incident wave and the electric field vector of the reflected wave are in opposite directions and they offset each other, as a result, the light strength on the vicinity of the interface weakens. There is hence the disutility that the light absorption amount of the sensitizing dye adsorbed onto the interface is inhibited, and the improvement of this disutility is also demanded.
The image quality variation of a red-sensitive layer by changing the location of the red-sensitive layer in a color photographic material comprising a blue-sensitive layer, a green-sensitive layer and a red-sensitive layer is described in Journal of Imaging Science and Technology, Vol. 38, pp. 32 to 35 (1994). If the location of a red-sensitive layer is changed, however, the image qualities of other photosensitive layers are deteriorated and the entire color balance also lowers, which produces a disadvantageous result.
Addition of TiO2 particles having a primary particle diameter of from 1 to 100 nm to a photo-insensitive layer as a UV absorber is disclosed in JP-A-10-62904, U.S. Pat. Nos. 5,731,136 and 5,736,308. They propose to use TiO2 particles which are not deteriorated with the lapse of time as a UV absorber in place of conventional organic UV absorbers which are deteriorated with aging, and to use TiO2 particles in a layer nearer to the light source than the color image-forming layer. They also propose to use as the TiO2 those described in Gunter Buxbaum, Industrial Inorganic Pigments, pp. 227 to 228, VCH Weinheim, Tokyo (1993). These particles certainly comprise small primary particles, but they are particles in which 90 mol % or more of the entire particles are occupied by particles comprising 30 or more primary particles which are three dimensionally agglomerated with one another and having three dimensional structure. They are inappropriate particles for the object of the present invention. Further, the foregoing patents do not aim to inhibit light scattering of AgX grains by increasing the refractive index of the binder in a photosensitive layer, so that this technique is different from the object of the present invention.
A technique of mixing a colloidal silica to an AgX emulsion layer to improve a pressure characteristic is disclosed in JP-A-4-241551 and JP-A-5-53237, and a technique of super-rapid low replenishing development process is disclosed in JP-A-9-269560. However, the refractive index of the foregoing colloidal silica to the light having a wavelength of 500 nm is lower than that of gelatin (1.546), therefore, this technique cannot make the refractive index of a dispersion medium layer high.
On the other hand, a silver halide photographic material containing TiO2 fine particles in the emulsion layer is disclosed in EP-A-930532 but this technique is different from the technique of the present invention in the point that the above photographic material is not subjected to desilvering processing after development.
An object of the present invention is to provide a silver halide photographic material which is further improved in sensitivity and image quality.
The above object of the present invention has been achieved by the following items (i.e., the following embodiments and preferred embodiments of the present invention).
(I) Embodiments of the Present Invention
(1) A silver halide photographic material comprising a support having provided thereon at least one silver halide emulsion layer, wherein the silver halide emulsion layer contains, in the dispersion medium phase of the emulsion, one or more kinds (preferably from 1 to 20 kinds, and more preferably from 2 to 10 kinds) of inorganic fine particles having a refractive index of from 1.62 to 3.30(preferably from 1.70 to 3.30, and more preferably from 1.80 to 3.10) to the light having a wavelength of 500 nm, the total weight of the fine particles contained in the unit volume of the dispersion medium phase is from 1.0 to 95 wt % (preferably from 5 to 90 wt %, and more preferably from 15 to 70 wt %), the dispersion medium phase containing the fine particles is substantially transparent to the photosensitive peak wavelength light of the emulsion layer, and the photographic material is exposed and processed in the development process comprising at least a developing step and a fixing step. The silver halide photographic material preferably has the refractive index of the dispersion medium phase to the light having a wavelength of 500 nm higher by 0.05 to 0.90(preferably from 0.12 to 0.90, and more preferably from 0.20 to 0.90) than the refractive index of the time when the dispersion medium phase does not contain the inorganic fine particles, the light reflection strength of the emulsion layer to the photosensitive peak wavelength light of the emulsion layer is reduced due to the presence of the fine particles to 0.0 to 95% (preferably from 0.0 to70%, and more preferably from 2.0 to 40%) of the light reflection strength of the time when the emulsion layer does not contain the inorganic fine particles, and the below-described Z1 value of the entire photographic image finally obtained through all the steps of development process is from 0.0 to 0.70 (preferably from 0.0 to 0.20, more preferably from 0.0 to 0.0S, and most preferably from 0.0 to 0.010).
Z1=[(the molar rate of the silver halide remaining in the finally obtained entire photographic image)/(the molar rate of the silver halide remaining in the entire photographic image obtained after development alone)]
(2) The silver halide photographic material as described in the above item (1), wherein from 50 to 100% (preferably from 80 to 100%, and more preferably from 95 to 100%) of the total projected area of the silver halide grains in the at least one silver halide emulsion layer are tabular grains having an aspect ratio (diameter/thickness) of from 2.0 to 300 ( preferably from 4.0 to 300, and more preferably from 4.0 to 100), a thickness of from 0.01 to 0.50 xcexcm (preferably from 0.01 to 0.30 xcexcm), and a diameter of from 0.1 to 30 xcexcm (preferably from 0.1 to 10 xcexcm, and more preferably from 0.1 to 5.0 xcexcm).
(3) The silver halide photographic material as described in the above item (2), wherein the tabular grains have a variation coefficient of thickness distribution of from 0.01 to 0.30 (preferably from 0.01 to 0.20), and a variation coefficient of diameter distribution of from 0.01 to 0.30 (preferably from 0.01 to 0.20, and more preferably from 0.01 to 0.10).
(4) The silver halide photographic material as described in the above item (1), (2) or (3), wherein the number of the inorganic fine particles is from 0.5 to 1012 (preferably from 2.0 to 1012, and more preferably from 10 to 1012) per one tabular grain.
(5) The silver halide photographic material as described in the above item (1), (2), (3) or (4), wherein the photographic material is a color photographic material comprising a support having multilayer-coated thereon at least a blue-sensitive layer, a green-sensitive layer and a red-sensitive layer.
(6) The silver halide photographic material as described in the above item (5), wherein the blue-sensitive layer, green-sensitive layer and red-sensitive layer respectively comprise one or more layers, and when taking it that the blue-sensitive layer comprises B1, B2, B3 . . . Bm1, green-sensitive layer-comprises G1, G2, G3 . . . Gm1, and red-sensitive layer comprises R1, R2, R3 . . . Rm1, in order nearer to the subject, the silver halide grains in one to three layers (preferably two or three layers, and more preferably three layers or three sets of layers) of B1, G1 and R1, [preferably (B1 and B2), (G1 and G2), and (R1 and R2), more preferably (B1, B2 and B3), (G1, G2 and G3), and (R1, R2 and R3), and still more preferably (B1, B2, B3 . . . Bm1), (G1, G2, G3. . . Gm1), and (R1, R2, R3 . . . Rm1)], are tabular grains as described in the above item (2) or (3).
(7) The silver halide photographic material as described in the above item (5) or (6), wherein the blue-sensitive layer is arranged nearest to the subject, the blue-sensitive layer comprises one or more layers, the silver halide grains contained in at least the layer having the highest sensitivity of the one or more layers are tabular grains as described in the above item (2), and the thickness of the tabular grains is prescribed so that the reflected light strength (A3) to the photosensitive peak wavelength light of the green-sensitive layer and the photosensitive peak wavelength light of the red-sensitive layer falls within the range defined by equation (a-1): Equation (a-1): Main planes of various tabular grains having the same condition excepting the thickness are subjected to incidence at the incident angle of 5xc2x0 with the beam of the photosensitive peak wavelength light, the reflected light strength is measured in the direction of the reflection angle of 5xc2x0, and when the reflected light strength with the highest strength is taken as A1, and the reflected light strength with the lowest strength is taken as A2, the range of the reflected light strength (A3) is defined as {A2xcx9c[A2+b1(A1xe2x88x92A2)]}, wherein b1 is 0.47, (preferably 0.30, and more preferably 0.12).
(8) A silver halide color photographic material comprising a support having provided thereon at least one red-sensitive silver halide emulsion layer, at least one green-sensitive silver halide emulsion layer, and at least one blue-sensitive silver halide emulsion layer, wherein the silver halide color photographic material satisfies at least one of the following items (i) to (v):
(i) At least one silver halide emulsion layer contains tabular silver halide grains, and the tabular grains have a lower spectral reflectance than the spectral reflectance of the tabular silver chloride grains having the same thickness;
(ii) At least one silver halide emulsion layer contains tabular silver halide grains, the average thickness of the tabular grains is smaller than the thickness of the grains in the layer which give the maximum value of spectral reflectance, and the spectral reflectance at the average thickness is 90% or less of the maximum value of spectral reflectance;
(iii) In the above item (ii), the silver halide grains having equivalent-circle diameter of 0.6 xcexcm or less accounts for 20% or less of the silver halide grains in the layer in terms of the projected area;
(iv) At least one spectral sensitive silver halide emulsion layer comprises two or more emulsion layers containing tabular grains, and the average grain thickness of the silver halide grains contained in at least one layer of these two or more layers other than the layer farthest from the support falls within the range of the thickness which gives the spectral reflectance of 80% or more of the maximum spectral reflectance of the tabular grains; and
(v) In the above item (iv), the layer farthest from the support satisfies the condition in item (ii) or (iii).
(9) A silver halide color photographic material comprising a support having provided thereon at least one red-sensitive silver halide emulsion layer, at least one green-sensitive silver halide emulsion layer, and at least one blue-sensitive silver halide emulsion layer, wherein at least one silver halide emulsion layer contains inorganic fine particles having a particle diameter of 100 nm or less and tabular silver halide grains having a thickness of less than 0.09 xcexcm.
(10) The silver halide photographic material as described in the above item (8), wherein at least one silver halide emulsion layer contains inorganic fine particles having a particle diameter of 100 nm or less.
Other preferred embodiments of the present invention are described below.
(11) The silver halide photographic material as described in the above item (5), wherein the green-sensitive layer comprises one or more layers, the silver halide grains contained in at least the layer having the highest sensitivity of the one or more layers are tabular grains as described in the above item (2), and the thickness of the tabular grains is prescribed so that the reflected light strength to the photosensitive peak wavelength light of the red-sensitive layer falls within the range defined by equation (a-1).
(12) The silver halide photographic material as described in the above item (5), wherein the red-sensitive layer comprises one or more layers, the silver halide grains contained in at least the layer having the highest sensitivity of the one or more layers are tabular grains as described in the above item (2), and the thickness of the tabular grains is prescribed so that the reflected light strength to the photosensitive peak wavelength light of the red-sensitive layer falls within the range defined by equation (a-1).
(13) The silver halide photographic material as described in the above item (5), wherein the blue-sensitive layer comprises from 2 to 7 layers, preferably from 3 to 5 layers, and when taking it that the blue-sensitive layer comprises first layer, second layer . . . m1th layer, in order from the highest sensitivity, the AgX grains in each layer of the second layer, preferably the second and the third layers, and more preferably the second layer . . . the m1th layer, are tabular grains as described in the above item (2), and the thickness of the tabular grains is prescribed so that the reflected light strength to the photo-sensitive peak wavelength light of the green-sensitive layer and the photosensitive peak wavelength light of the red-sensitive layer falls within the range defined by equation (a-1).
(14) The silver halide photographic material as described in the above item (5), wherein the green-sensitive layer comprises from 2 to 7 layers, preferably from 3 to 5 layers, and when taking it that the green-sensitive layer comprises first layer, second layer . . . m1th layer, in order from the highest sensitivity, the AgX grains in each layer of the second layer, preferably the second and the third layers, and more preferably the second layer . . . the math layer, are tabular grains as described in the above item (2), and the thickness of the tabular grains is prescribed so that the reflected light strength to the photosensitive peak wavelength light of the red-sensitive layer falls within the range defined by equation (a-1).
(15) The silver halide photographic material as described in the above item (5), wherein the red-sensitive layer comprises from 2 to 7 layers, preferably from 3 to 5 layers, and when taking it that the red-sensitive layer comprises first layer, second layer . . . m1th layer, in order from the highest sensitivity, the AgX grains in each layer of the second layer, preferably the second and the third layers, and more preferably the second layer . . . the m1th layer, are tabular grains as described in the above item (2), and the thickness of the tabular grains is prescribed so that the reflected light strength to the photo-sensitive peak wavelength light of the red-sensitive layer falls within the range defined by equation (a-1).
(16) The silver halide photographic material as described in the above item (5), wherein the thickness of the tabular grains in the first blue-sensitive layer, preferably the first layer and the second layer, is prescribed so that the reflected light strength to the photosensitive peak wavelength light of the blue-sensitive layer falls within the range defined by equation (a-1), wherein b1 is 0.70, preferably 0.55.
(17) The silver halide photographic material as described in the above item (1), wherein the photographic material has one or more photosensitive layers, at least one photosensitive layer comprises two or more AgX-containing emulsion layers, and when taking it that the AgX-containing emulsion layer comprises first layer, second layer . . . m1th layer, in order nearer to the subject, at least one layer of the second layer to the lowest rank layer is a reflective layer in order to effectively reflect the photosensitive layer, the AgX grains contained in the reflective layer are tabular grains as described in the above item (2), and when taking it that the average grain diameter of the AgX grains contained in the layer ahead of one is d1, the average value d2 is from 1.10d1 to 100d1, preferably from 1.50d1 to 100d1, more preferably from 2.0d1 to 100d1, and still more preferably from 4.0d1 to 100d1.
(18) The silver halide photographic material as described in the above item (17), wherein the thickness of the tabular grains contained in the reflective layer is prescribed so that the reflected light strength (A4) to the photosensitive peak wavelength light of the photosensitive layer falls within the range defined by the following equation (a-2): Equation (a-2) Main planes of various tabular grains having the same condition excepting the thickness are subjected to incidence at the incident angle of 5xc2x0 with the beam of light of the photosensitive peak wavelength light, the reflected light strength is measured in the direction of the reflection angle of 5xc2x0, and when the reflected light strength with the highest strength is taken as A1, and the reflected light strength with the lowest strength is taken as A2, the range of said reflected light strength (A4) is defined as {A1xcx9c[A1+b2(A1xe2x88x92A2)]}, wherein b1 is 0.47, preferably 0.30, and more preferably 0.20.
(19) The silver halide photographic material as described in the above item (18), wherein the sensitivity of the tabular grains contained in the lowest layer (a sample monolayer-coated on a transparent support is exposed through an optical wedge with the photosensitive peak wavelength light of the photosensitive layer, development processed, and when the exposure amount giving the middle point density on the characteristic curve of the sample obtained is taken as (E1), a log(E1) value is the sensitivity) is higher by 0.10 to 2.0, preferably by 0.2 to 1.0, than the sensitivity of the tabular grains contained in the layer of a rank ahead of one (a-log(E2) value obtained by the same definition).
(20) The silver halide photographic material as described in the above item (2) or (3), wherein the tabular grains have {111} planes as main planes and two twin planes parallel to the main planes, the distance between the twin planes is from 0.3 to 50 nm, preferably from 0.3 to 30 nm, the configuration of the main planes are hexagons, or hexagons having rounded corners, and a ratio of adjacent side lengths of the hexagon or a hexagon formed by prolonging the straight lines of the sides ((a side length of the longest side/a side length of the shortest side) in one tabular grain) is from 1.0 to 2.0.
(21) The silver halide photographic material as described in the above item (2) or (3), wherein the tabular grains have {100} planes as main planes, the configuration of the main planes are right angled parallelograms or right angled parallelograms having rounded corners, and a ratio of adjacent side lengths of the parallelogram or a parallelogram formed by prolonging the straight lines of the sides ((a side length of the longest side/a side length of the shortest side) in one tabular grain) is from 1.0 to 3.5, preferably from 1.0 to 2.0.
(22) The silver halide photographic material as described in the above item (2), wherein the tabular grains have an epitaxial part (which is called a guest grain) on the peripheral part of the projected configuration which is different in a Cl content, a Br content or an I content from the average halogen composition of the surface layer of the tabular grain (a layer of a distance of from 0 to 3.0 nm from the surface of the grain) by 5.0 to 100 mol % (preferably from 20 to 100 mol %, and more preferably from 40 to 100 mol %), the total amount of the epitaxial part is from 0.001 to 0.30 (preferably from 0.003 to 0.20) per mol of the host grain, and the peripheral part is the region from 60 to 100% (preferably from 80 to 100%, and more preferably from 90 to 100%) of the distance in a straight line from the central part to the peripheral part with the central part as the starting point.
(23) The silver halide photographic material as described in the above item (1), wherein the inorganic fine particles are pulverized in an aqueous solution containing from 001to 10 wt % (preferably from0.1 to 5.0 wt% ), of a water-soluble dispersion medium containing one or more of a water-soluble polymer, a surfactant, a photographic antifoggant, an onium base-containing compound, a phosphoric acid, a silicic acid, and an organic acid), and the pulverized size of the inorganic fine particles is from 108xe2x88x92to 0.5 times (preferably from 108xe2x88x92to 0.1 times) of the original average volume.
(24) The silver halide photographic material as described in the above item (1) or (2), wherein from 10 to 100% (preferably from 30 to 100%, and more preferably from 60 to 100%) of the entire molar amount of the inorganic fine particles are titanium oxide, and when Fe is contained, the weight of Fe2O3 based on (TiO2+Fe2O3) is from 0.0 to 1.0 wt % (preferably from 0.0 to 0.5 wt %, and more preferably from 0.0 to 0.1 wt %).